Annual average net radiation determined from 1985 to 1986. Net radiation
is the difference between incoming solar radiation that is absorbed by Earth
and outgoing infrared radiation from Earth that is lost to space. The net
radiation is generally positive at low latitudes (increases in heating represented
by oranges, reds, and pinks) and negative at high latitudes (increases in
cooling represented by greens and blues).

Annual average net cloud radiative forcing (bottom) determined from 1985
to 1986. Net cloud forcing is the result of two opposing effects: (1) greenhouse
heating by clouds (or positive forcing)--clouds trap heat coming from Earth's
surface that would otherwise be lost to space, and (2) cooling by clouds
(or negative forcing)--clouds reflect incoming solar radiation back to space.
The relatively large areas where cooling is the greatest are represented
by colors that range from yellow to green to blue. In some areas, the effect
of the clouds is to produce some warming as shown by colors that range from
orange to red to pink. Overall, clouds have the effect of lessening the
amount of heating that would otherwise be experienced at Earth's surface
(Earth Radiation Budget Experiment data on the Earth Radiation Budget Satellite
and the NOAA-9 satellite. Data processed at NASA Langley Research Center;
images produced at the University of Washington).